function y = flipMDL(model,arg)


switch arg,
    case 'Ox'
        for i=1:size(model,3),
                model(2,:,i) = -model(2,:,i);
        end
    case 'Oy'
        for i=1:size(model,3),
                model(1,:,i) = -model(1,:,i);
        end
    otherwise
        error('Unknown flipping axis.');
end

    y = model;
end